1. Field
This document relates to a stereoscopic image display device for displaying a three dimensional (3D) stereoscopic image (hereinafter, referred to as a 3D image) and a driving method thereof.
2. Related Art
A stereoscopic image display device displays a 3D image using a stereoscopic technique or an autostereoscopic technique.
The stereoscopic technique, which uses a parallax image of left and right eyes of a user with a high stereoscopic effect, includes a glass method and a non-glass method both of which have been put to practical use. In the non-glass method, an optical plate, such as a parallax barrier or the like, for separating an optical axis of the left and right parallax image is installed in front of or behind a display screen. In the glass method, a left and right parallax image is displayed on a liquid crystal display panel by changing a polarization direction of the left and right parallax image, and a stereoscopic image is implemented using polarized glasses or liquid crystal shutter glasses.
The glass method is roughly classified into a first polarization filter method using a patterned retarder film and polarization glasses, a second polarization filter method using a switching liquid crystal layer and polarization glasses, and a liquid crystal shutter glass method. In the first and second polarization filter methods, the transmission of a 3D image is low due to the patterned retarder film or switching liquid crystal layer disposed on the liquid crystal display panel to act as a polarization filter.
In the liquid crystal shutter glass method, a left eye image and a right eye image are alternately displayed for each frame on a display device, and left- and right-eye shutters of the liquid crystal shutter glasses are opened and closed in synchronization with this display timing to implement a 3D image. The liquid crystal shutter glasses create a binocular parallax in a time-division manner by opening only the left-eye shutter during an nth frame period in which the left-eye image is displayed and opening only the right-eye shutter during an (n+1)th frame period in which the right-eye image is displayed.
The stereoscopic image display device may comprise a hold type display device such as a liquid crystal display (LCD). 3D crosstalk seen as ghost images occurs in the liquid crystal display due to low response speed of liquid crystals at a time when the liquid crystal display switches from the left-eye image to the right-eye image or from the right-eye image to the left-eye image.
In other words, assuming that, as shown in FIG. 1, the left-eye shutter of the liquid crystal shutter glasses ST is opened during the nth frame period Fn and the right-eye shutter of the liquid crystal shutter glasses ST is opened during the (n+1)th frame period Fn+1, left-eye image data L(Fn) is sequentially written to the liquid crystal display during the n-frame period Fn, and right-eye image data R(Fn+1) is sequentially written thereto during the (n+1)th frame period (Fn+1). While the left-eye shutter of the liquid crystal shutter glasses ST is opened within the nth frame period Fn, some pixels, whose liquid crystal response to the left-eye image L(Fn) is not completed, are affected by the right-eye image data R(Fn−1) of the (n−1)th frame. Accordingly, the observer's left eye sees part of the right-eye image R(Fn−1) of the (n−1)th frame, as well as the left-eye image L(Fn) of the nth frame, in an overlapped manner. Moreover, while the right-eye shutter of the liquid crystal shutter glasses ST is opened within the (n+1)th frame period Fn+1, some pixels, whose liquid crystal response to the right-eye image R(Fn+1) is not completed, are affected by the left-eye image data L(Fn) of the nth frame. Accordingly, the observer's left eye sees part of the left-eye image L(Fn) of the nth frame, as well as the right-eye image R(Fn+1) of the (n−1)th frame, in an overlapped manner.
3D crosstalk deteriorates image quality and causes dizziness.